The present invention is directed to a one-piece, molded plastic, or the like, closure that may be threaded onto the finish or neck of a container, and in which a tamper-indicating band is joined to the bottom of the closure skirt by a series of frangible bridges. An inwardly and upwardly turned flexible, stop band is molded inside the indicator band and in combination with a radial bead on the container finish will resist removal of the closure without rupture of the frangible bridges.
Tamper-indicating closures are not new and one recently patented example can be found in U.S. Pat. No. 4,394,918, issued to Jean Grussen on July 26, 1983. In this patent a threaded closure carries a hold ring that is joined to the bottom of the cap skirt by a series of breakable tabs and the hold ring has an inside diameter that is at least equal to the outside diameter of the cap skirt. A plurality of lock lugs supported on the ring are inclined upwardly and inwardly and are intended to hook behind a collar or mating ring on the container neck to prevent the hold ring from being lifted off the container neck when the cap is unscrewed. An unbreakable flange is provided between the cap skirt and the ring and serves as a hinge for the cap when it is unscrewed.
Other tamper-indicating closures that thread on the containers are made fairly simple, but these tamper-indicating rings generally require cooperating, specially designed, means on the container.
Some other tamper-indicating systems have been used in which a frangible band is formed at the bottom of the closure skirt and requires the actual destruction of the band before the closure can be unscrewed. These also may require special ramps and ledges to be formed on the container shoulders or necks. The problem with these systems is that once the band is removed and discarded, it may not be readily apparent that the closure has been unscrewed.
Much of the same can be said for the systems that use heat shrunk or stretch bands that engage the closure and the container. Furthermore, heat shrinking adds an additional step to the sealing process and requires special equipment beyond the normal threaded closure applying machines.